Polymerization processes which are based on unsaturated esters are well documented in the art. Controlling the polymer's physical properties, such as thermal stability, is a complicated task, because physical properties are affected by several parameters which are not always recognized or simple to handle.
The invention, as said, is concerned with the preparation of polymers of Formula I. Production of the monomeric unit is, of course, the first step in the polymerization process. IL 89791 discloses a process for the preparation of bromo-substituted aromatic esters of certain .alpha.,.beta.-unsaturated acids. GB 1,516,212 discloses a procedure for preparing unsaturated esters, which may later serve as reactive monomers for polymeric materials. One Example of such an unsaturated ester is pentabromobenzyl acrylate (PBB-MA), obtained by reacting, according to the procedure given in GB 1,516,212, pentabromobenzyl chloride with an alkali metal salt of .alpha.,.beta.-unsaturated acid, in particular, an acrylic acid. This process is carried out in a protic solvent (methoxyethanol). Direct polymerization, when performed according to a procedure disclosed in the art (GB 1,547,839) yields a polymer, poly(pentabromobenzyl acrylate), the thermal stability of which is limited. The Isothermal Gravimetric Analysis (ITGA 290.degree. C./30 min) parameter of the aforementioned polymer is of the order of 35%-50% weight loss.
It is a purpose of the present invention to provide a process for the preparation of polymers of Formula I, characterized by an improved thermal stability.
It is another object of the invention to provide polymers which exhibit high thermal stability.
It is a further object of the invention to provide a one-pot process, in which the polymeric product is obtained from the monomeric unit of formula Ia: ##STR4## wherein n+m=1 through 5, which is made in situ from a compound of the following formula: ##STR5## wherein n+m=1 through 5.
It is yet another object of the invention to provide a one-pot process, in which the polymeric product is obtained from the monomeric unit which is made from a compound of Formula II. The compound of formula II, in turn, is prepared in situ from a compound of formula (III): ##STR6## wherein n+m=1 through 5.
Other objects of the invention will become apparent as the description proceeds.